The present invention relates generally to an apparatus for testing the purity of precious metals, and, more particularly, to a testing apparatus that identifies the silver content in a specimen being tested by the apparatus.
A precious metal testing apparatus is shown in U.S. Pat. No. 5,888,362, issued to Lloyd V. Fegan, Jr., on Mar. 30, 1999. This testing apparatus provides a portable device that can provide accurate analysis of the quality of the precious metal, particularly gold and platinum, being tested by utilizing a hand-held probe having an electrode embedded in an electrolyte contained within a reservoir formed in the probe. The testing apparatus generates a galvanic current through the metal being tested from a battery, the strength of the current being proportionate to the quality of the precious metal being tested. In the Fegan patent, a meter circuit measures the extent of galvanic action of dissimilar metals in the presence of an electrolyte, one of the metals being the sample being tested for quality. Thus, the invention is useful for testing the metal content of gold coins, art objects jewelry, and the like, by reason that the probe can simply be touched against the object being tested to provide a reading representing the quality of the precious metal in the object.
The hand-held probe in the aforementioned precious metal testing apparatus is typically in the form of a pen having a fibrous tip from which a small amount of electrolyte is deposited onto the object being tested. The meter attached to the probe continuously measures the strength of the galvanic current and compares the result with a known point of reference for the type of precious metal being tested, whereby the percentage of precious metal within the object being tested will be known. This measurement process by the meter and pen is completed within a few hundredths of a second, thus providing an efficient manner in which the quality of precious metal can be determined. However, even though the measurement process is fast, the strengths of the galvanic reaction when reacted with gold or platinum are very weak.
The Fegan gold testing apparatus, however, is not very effective in testing for the content of silver in an object. Silver is highly conductive and the current from the pen probe easily passes through the silver specimen causing the needle to bottom out. Other known methods of testing for silver involves exposing the silver (AG) samples to a chemical test. The concentration (i.e. the purity) of the silver in the specimen is the based on a visual inspection of the chemical reaction reflecting a change in color of the exposed chemical. Such visual inspection tests can be somewhat subjective and the accuracy of the test is dependent on the experience of the person conducting the chemical test.
It would be desirable to provide an electronic apparatus that would provide an accurate and efficient testing of a specimen to be able to determine the concentration of the silver content within the sample.